Treasury Secretary Steven Mnuchin said this week that the Trump administration wanted tax reform in place by the start of Congress' August recess, a schedule that would be hard to keep if the goal was just to name a post office. Photographer: Kevin Dietsch/Pool via Bloomberg

Donald Trump’s insistence that his tax and spending plans will provide an immediate kick to the U.S. economy and Wall Street’s belief that the new administration’s budget policies will lead to a quick boost in corporate profits now need to be tempered with a big dose of economic reality: The president’s promised fiscal stimulus isn’t going to be enacted or take effect any time soon. If it happens at all, the soonest the economy will begin to feel the impact of a Trump stimulus is in federal fiscal year 2018, that is, starting 7 months from now on October 1.

AN ACA and tax reform delay will also have an impact on when Congress will be able to deal with the other issues -- like the Trump infrastructure plan -- that were supposed to stimulate the economy, as well as the amount of time Congress will have to do everything else.

Politics aside, pure logistical considerations will also delay the impact of the Trump plans to stimulate the economy.

For example, while Trump said he wants to increase the military budget by up to $40 billion this year, the truth is that very little of that will be spent quickly. Even if Congress includes the additional funding in the continuing resolution that will be needed by April 29th to prevent a government shutdown, which is hardly a sure thing, most of these additional funds will be devoted to procurement and that spends out very slowly. If the historical pattern holds, no more than about $4 billion of the $40 billion will be spent in calendar year 2017, an insignificant amount in a total U.S. economy that is approaching $19 trillion.

Infrastructure is another example. The Trump plan supposedly is for $1 trillion in new spending over the next 10 years. But in spite of all the talk about “shovel-ready,” the truth is that infrastructure projects are notorious for how long they take to begin. Here too, unless the new projects are a sharp departure from all previous experience with infrastructure, very little – as in almost none – will be started in 2017 and only a handful of projects will begin in 2018. The biggest economic impact will start to be felt in 2019-2020.

But given the multiple enormous controversies surrounding tax reform and the extraordinary procedural impediments to getting it passed in the House and Senate, getting tax reform enacted by the end of this July will be a legislative miracle. Even a more likely December 31, 2017, is starting to look like a reach.

Any enactment date after September 1 would substantially limit tax reform’s economic impact this year. December 31 would limit it almost completely.